Four new species of Pseudoplagiostoma (Pseudoplagiostomataceae, Diaporthales) based on morphology and multi-locus phylogeny from China.

Pseudoplagiostoma fungi are globally widespread, encompassing plant-pathogenic, saprophytic, and endophytic fungal species associated with diverse plant hosts. Four Pseudoplagiostoma isolates were recovered from diseased leaves of Artocarpus hainanensis, Cinnamomum sp., Mallotus hookerianus, and Trachelospermum jasminoides in China. These were identified and formally described in the present study. Species boundaries were delineated using an integrative approach combining molecular phylogenetic analyses and morphological comparisons with closely related taxa. Phylogenetic analyses were conducted on concatenated LSU, ITS, RPB2, TEF1-α, and TUB2 sequence datasets using both maximum likelihood and Bayesian inference methods. The results demonstrated that these four isolates form well-supported, independent monophyletic lineages, clearly distinct from all previously described Pseudoplagiostoma species. Morphological characterization of colonies, conidiogenous cells, and conidia revealed stable phenotypic differences from closely related species, further corroborating their taxonomic novelty. Accordingly, four new species of Pseudoplagiostoma are proposed: Ps. artocarpi, Ps. cinnamomi, Ps. malloti, and Ps. trachelospermi.